Hello,
I'm trying to calculate the IRR for multiple events in a longitudinal
study dataset.
I therefore stset the data:
stset Event_date if disease_no==0 & cond==1, id(ID)
failure(disease_yes==1) origin(time birthdate) enter(time birthdate)
exit(Visit==50)
replace _t0=_t0+t_ex
Then I'm splitting the dataset to exclude non important time periods:
stsplit x_split, at(60 761) trim
Now, when I calculate the rate, I receive something like:
strate gene if x_split==60,per(365.25)
GT Rate
CC 0.64
CT 0.53
TT 0.55
-> the rate of disesase-attacs is lower for the CT/TT-genotype, right?
Now, when I calculate the inicidence rate ratio (IRR) on the same st-
set data, I get:
xi: poisson _events i.gene if risktime>0&x_split==60,
exposure(risktime) irr
GT IRR(CI) P
CC 1
CT 1.11 (1.03 - 1.19) 0.005
TT 1.14 (1.04 - 1.24) 0.005
According to these results, the IRR is HIGHER for the CT/TT-genotype.
This is weird. I guess there is something wrong.
Any help would be appreciated!
Thanks,
Chris
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